How to judge the day is next day via moment()

Question

I use Moment to handle time in my code.

Here is a question:

I want to judge two times, if now is the next day of last_take_time

If I write like this:

   if not last_take_time? or (now.dayOfYear() - last_take_time.dayOfYear() is 1 )
      do_something()

There is a problem when last_take_time is the end day of a year.

I am newbie with JavaScript and Moment, but I think there is a right way to judge this.

Thanks!

Answer 1

If you use dayOfWeek() then it is fairly easy to add an extra clause to test for the tricky case of Sunday / Monday:

if(last_take_time && (now.dayOfWeek() - last_take_time.dayOfWeek() == 1 
        || (now.dayOfWeek() == 1 && last_take_time.dayOfWeek() == 7)))
    do_something();

This is easier than dealing with the dayOfYear() because of having to deal with leap years.

Edit

Ah ok, I understand, you make a valid point - the answer above will return false positives when the days are more than a week apart. We can add a clause to account for this:

if(last_take_time && now.diff(last_take_time, 'days') < 3
        && (now.dayOfWeek() - last_take_time.dayOfWeek() == 1
        || (now.dayOfWeek() == 1 && last_take_time.dayOfWeek() == 7)))
    do_something();

The additional clause uses the moment.js method diff(): link to docs to account for the highlighted issue.